Atherectomy device supported by fluid bearings

ABSTRACT

A rotational atherectomy device for removing a stenotic tissue ( 330, 360 ) from a vessel ( 300 ) of a patient comprises a flexible hollow drive shaft ( 2 ) and an abrasive element ( 101, 102 ) mounted to the drive shaft proximal to and spaced from a solid support element ( 10, 10   s ) mounted at the distal end ( 6 ) of the drive shaft, the solid support element having a rounded outer surface and an outflow channel ( 20, 20   s ) with an outflow opening in said rounded outer surface. The drive shaft comprises a torque transmitting coil ( 4 ) and at least one fluid impermeable membrane ( 3 ) forming a fluid impermeable lumen for the antegrade flow (FF) of fluid into the outflow channel such that, during rotation of the drive shaft, a flow of fluid out of said outflow opening forms a fluid bearing between the rotating solid support element and the wall of the treated vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application based onPCT/EP2007/056499, filed Jun. 28, 2007, the content of which isincorporated herein by reference, and claims priority of GB PatentApplication No. 0613979.4, filed Jul. 13, 2006, the content of which isincorporated by herein by reference.

BACKGROUND OF THE INVENTION

1. Field

The present invention provides a rotational atherectomy device forremoving a stenotic lesion from within a vessel of a patient. Morespecifically, the invention relates to a rotational atherectomy devicefor removing or reducing stenotic lesions in blood vessels such as ahuman artery by rotating an abrasive element within the vessel topartially or completely ablate the unwanted material.

2. Description of the Related Art

Atherosclerosis, the clogging of arteries, is a leading cause ofcoronary heart disease. Blood flow through the peripheral arteries(e.g., carotid, femoral, renal, etc.), is similarly affected by thedevelopment of atherosclerotic blockages. A conventional method ofremoving or reducing blockages in blood vessels is known as totationalatherectomy. A long guidewire is advanced into the diseased blood vesseland across the stenotic lesion. A hollow drive shaft is then advancedover the guidewire. The distal end of the drive shaft terminates in aburr provided with an abrasive surface formed from diamond grit ordiamond particles. The burr is positioned against the occlusion and thedrive shaft rotated at extremely high speeds (e.g., 20,000-160,000 rpm).As the burr rotates, the physician slowly advances it so that theabrasive surface of the burr scrapes against the occluding tissue anddisintegrates it, reducing the occlusion and improving the blood flowthrough the vessel. Such a method and a device for performing the methodare described in, for example, U.S. Pat. No. 4,990,134 to Auth. It isalso known from U.S. Pat. No. 6,132,444 to Shturman (the instantinventor) et al., to provide a drive shaft with an abrasive elementeccentrically positioned proximally to and spaced away from the distalend of the drive shaft.

Rotational angioplasty (atherectomy) is frequently used to removeatherosclerotic or other blocking material from stenotic (blocked)coronary arteries and other blood vessels. However, a disadvantage withthis technique is that abraded particles can migrate along the bloodvessel distally and block very small diameter vessels includingcapillaries of the heart muscle itself. The effect of the particulatedebris produced by this procedure is of major concern to physicians whopractice in this field. Clearly, the existence of particulate matter inthe blood stream is undesirable and can cause potentiallylife-threatening complications, especially if the particles are over acertain size.

Although the potentially detrimental effect caused by the presence ofabraded particles in the blood vessels is reduced if they are very smallmicroparticles, it is much more preferable to remove from the treatedblood vessel any debris abraded or otherwise released from the stenoticlesion during treatment and thereby prevent migration of debris to otherlocations along the treated blood vessel.

A rotational atherectomy device, described in U.S. Pat. No. 5,681,336(to Clement et al.), has been proposed which attempts to preventmigration of abraded particles along the blood stream by removing theablated material from the blood vessel whilst the device is in use. Therotational atherectomy device known from U.S. Pat. No. 5,681,336 (toClement et al.) has a complicated construction and is difficult tomanufacture on a commercial scale.

A number of disadvantages associated with the known rotationalatherectomy devices have been addressed in WO 2006/126076, WO2006/126175 and WO 2006/126176 to Shturman (the instant inventor). Thepresent invention seeks to further improve rotational atherectomydevices known from these documents and other disadvantages associatedwith known atherectomy devices.

Two most preferred embodiments of the Rotational Atherectomy Device withSolid Support Elements are described in WO 2006/126076. Both embodimentscomprise an abrasive element and a pair of solid support elementsmounted to a hollow drive shaft formed from a torque transmitting coiland a fluid impermeable membrane. In both preferred embodiments, theabrasive element is located proximal to and spaced away from the distalend. The solid support elements described in WO 2006/126076 are rounded.One of them is located at the distal end of the drive shaft and isreferred to as the distal solid support element. The other is locatedproximal to and spaced away from the abrasive element and is referred toas the proximal distal support element.

In one embodiment of the invention described in WO 2006/126076, theabrasive element has its centre of mass spaced away from thelongitudinal or rotational axis of the drive shaft. In that embodiment,both the distal and the proximal solid support elements also have theircentres of mass spaced radially away from the longitudinal or rotationalaxis of the drive shaft, the centre of mass of each of the two solidsupport elements being located diametrically opposite to the centre ofmass of the abrasive element with respect to the longitudinal axis ofthe drive shaft so that the distal and proximal solid support elementsact as counterweights with respect to the abrasive element when thedrive shaft rotates. Most preferably, the distal and proximal solidsupport elements are located in the same longitudinal plane as thecentre of mass of the abrasive element, the longitudinal plane extendingthrough the longitudinal or rotational axis of the drive shaft.

In another embodiment described in WO 2006/126076, the abrasive elementand the solid support elements have their centres of mass coaxial withthe longitudinal or rotational axis of the fluid impermeable driveshaft.

In both embodiments described in WO 2006/126076, pressurised fluidenters treated vessel only through a distal end opening of the fluidimpermeable lumen of the drive shaft.

SUMMARY

According to the invention, there is provided a rotational atherectomydevice for removing a stenotic tissue from a vessel of a patient, thedevice comprising a rotatable, flexible, hollow drive shaft having adistal end, an abrasive element mounted to the drive shaft proximal toand spaced away from a distal solid support element mounted at thedistal end of the drive shaft, the distal solid support element having arounded outer surface and comprising an outflow channel extendingthrough the solid distal support element, the outflow channel having anoutflow opening in said rounded outer surface, the drive shaftcomprising a torque transmitting coil and at least one fluid impermeablemembrane forming a fluid impermeable lumen for the antegrade flow offluid along the torque transmitting coil into the outflow channel of thesolid distal support element such that, during rotation of the driveshaft, said outflow opening of the outflow channel is facing an innersurface of a vessel being treated so that a flow of fluid out of saidoutflow opening forms a layer of fluid between the solid distal supportelement and a wall of the treated vessel, said layer of fluid forming afluid bearing between the rotating solid distal support element and thewall of the treated vessel.

In a preferred embodiment, the fluid impermeable drive shaft is providedwith a solid proximal support element located proximal to and spacedaway from the abrasive element, the membrane that forms a fluidimpermeable lumen for the antegrade flow of fluid along the torquetransmitting coil into the outflow channel of the distal solid supportelement also forming a lumen for the antegrade flow of fluid along thetorque transmitting coil into an outflow channel extending through saidsolid proximal support element, the solid proximal support elementhaving a rounded outer surface, said outflow channel having an outflowopening in the rounded outer surface of the solid proximal supportelement such that, during rotation of the drive shaft, said outflowopening on the outer surface of the solid proximal support element isfacing an inner surface of a treated vessel so that a flow of fluid outof said outflow opening forms a layer of fluid between the solidproximal support element and a wall of the treated vessel, said layer offluid forming a fluid bearing between the rotating solid proximalsupport element and the wall of the treated vessel.

In one embodiment, the drive shaft preferably has a longitudinal axisand the solid distal support element has a centre of mass which iscoaxial with the longitudinal axis of the drive shaft, said distalsupport element having a plurality of outflow channels that extendthrough the distal support element in a radially outward direction withrespect to the longitudinal axis of the drive shaft and have theiroutflow openings spaced around the circumference of the solid distalsupport element such that, during rotation of the drive shaft, a flow offluid through the outflow openings forms a layer of fluid between thesolid distal support element and a wall of the vessel being treated,said layer of fluid forming a fluid bearing between the rotating soliddistal support element and the wall of the vessel being treated. In thisembodiment, the centre of mass of the abrasive element may either becoaxial with the longitudinal axis of the drive shaft or, spacedradially away from the longitudinal axis of the drive shaft.

In an embodiment where there is a solid proximal support element, thesolid proximal support element may have a centre of mass coaxial withthe longitudinal axis of the drive shaft, said proximal support elementhaving a plurality of outflow channels extending through the solidproximal support element in a radially outward direction with respect tothe longitudinal axis of the drive shaft and having their outflowopenings located around the circumference of the solid proximal supportelement such that, during rotation of the drive shaft, a flow of fluidout of the outflow openings forms a layer of fluid between the solidproximal support element and a wall of the vessel being treated, saidlayer of fluid forming a fluid bearing between the rotating solidproximal support element and the wall of the vessel being treated. Inthis embodiment, the centre of mass of the abrasive element may eitherbe coaxial with the longitudinal axis of the drive shaft or, spacedradially away from the longitudinal axis of the drive shaft.

In one embodiment, the solid distal support element may have its centreof mass spaced radially away from the longitudinal axis of the driveshaft in one direction so that it acts as a counterweight to theabrasive element, which has its centre of mass spaced radially away fromthe longitudinal axis of the drive shaft in a diametrically oppositedirection.

In an embodiment in which the abrasive element has its centre of massspaced radially away from a longitudinal axis of the drive shaft, thecentres of mass of both distal and proximal solid support elements maybe spaced radially away from a longitudinal axis of the drive shaft butin a direction diametrically opposite to the direction in which theabrasive element is spaced radially away from the longitudinal axis ofthe drive shaft so that the distal and proximal solid support elementsact as counterweights to the abrasive element.

It will be appreciated that there may be a plurality of outflow channelsin the solid distal support element in any of the embodiments of theinvention.

It should be emphasized that the present invention covers two mostpreferred embodiments in one of which the solid support elements areasymmetrical with respect to the longitudinal axis of the drive shaft.In the other preferred embodiment, the solid support elements aresymmetric with respect to the longitudinal axis of the drive shaft.However, it will be appreciated that, in all the embodiments, theasymmetric and symmetric solid support elements comprise outflowchannels located such that, in the rotating drive shaft, fluid flowingout of said channels forms fluid bearings between outer walls of saidsolid support elements and the wall of the treated vessel.

It should be noted that throughout this specification, reference is madeto “distal” and “proximal” ends and to flow of fluid in an “antegrade”and “retrograde” direction. For the avoidance of doubt, the distal endis considered to refer to the end of the device which is inserted intothe vessel in the body of the patient and the proximal end is the end ofthe device which remains outside the body of the patient and which canbe connected to a handle assembly for both rotating and longitudinallymoving the drive shaft within the treated vessel. “Antegrade” flowrefers to a direction of flow from the proximal towards the distal endof the device. Similarly, “retrograde” flow refers to a direction offlow in the opposite direction, i.e. from the distal towards theproximal end of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, and with reference to the accompanying drawings, in which:

FIG. 1 illustrates in a longitudinal cross-section a distal portion ofone preferred embodiment of the rotational atherectomy device of theinvention, this embodiment comprising asymmetric solid support elementsand illustrating the location of outflow channels which extend throughsaid solid support elements;

FIG. 2 illustrates the device of FIG. 1 located in a vessel beingtreated and shows how the device can be used to abrade a stenotic lesionwhile forming fluid bearings between rounded outer surfaces ofasymmetric solid support elements located distal and proximal to theabrasive element;

FIG. 3 illustrates in a longitudinal cross-section a distal portion ofone preferred embodiment of the rotational atherectomy device of theinvention, this embodiment comprising symmetric solid support elementslocated distal and proximal to the symmetric abrasive element andillustrates location of outflow channels which extend through said solidsupport elements; and

FIG. 4 illustrates the device of FIG. 3 located in a vessel beingtreated and shows how the device can be used to abrade a stenotic lesionin a curved vessel. This Figure also shows how fluid bearings are formedbetween the rounded outer surfaces of symmetric solid support elementsand the wall of the treated vessel.

DETAILED DESCRIPTION

In FIGS. 1 to 4, the antegrade flow of fluid is indicated by arrows “FF”and the flow of fluid in a retrograde direction is indicated by arrowsmarked “R”. Abraded particles AP abraded from the stenotic lesion 330are aspirated into a lumen of a drive shaft sheath 400 so that theretrograde flowing fluid and the abraded particles entrained in saidfluid can be removed from the treated vessel and out of the patient'sbody.

Referring to the drawings, there is shown a rotational atherectomydevice for removing a stenotic lesion from within a vessel of a patientusing an abrasive element mounted to a rotatable, flexible, hollow driveshaft formed by a torque transmitting coil and a fluid impermeablemembrane. The drive shaft has a longitudinal axis of rotation and isprovided with two rounded solid support elements. Each of the two solidsupport elements is spaced away from the abrasive element and includesat least one outflow channel which is directed radially outward andcommunicates a lumen of the drive shaft with a vascular space of thetreated vessel, one of said solid support elements is a distal solidsupport element and is located at a distal end of the drive shaft andthe other is a proximal solid support element and is located proximal tothe abrasive element.

In a preferred embodiment, each of the distal and proximal solid supportelements has a rounded surface and is spaced equally from the abrasiveelement which extends around the entire circumference of the driveshaft.

In one embodiment of the invention the abrasive element and each of thetwo solid support elements are symmetric with respect to the rotational(longitudinal) axis of the drive shaft. In another embodiment of theinvention the abrasive element and the solid support elements have theircentres of mass spaced radially away from the rotational Longitudinal)axis of the drive shaft.

Each outflow channel has its own axis and each of the solid supportelements has at least one outflow channel located such that its axiscomprises an acute angle of at least seventy five (75) degrees with thelongitudinal (rotational) axis of the drive shaft. In a preferredembodiment each of the solid support elements has at least one outflowchannel located such that its axis comprises an angle of about (90)degrees with the longitudinal (rotational) axis of the drive shaft. Inthe most preferred embodiment of the invention each of the symmetricsolid support elements has at least a few outflow channels equallyspaced around the maximum circumference of the support element, each ofsaid outflow channels having an axis which comprises an angle of aboutninety (90) degrees with the longitudinal (rotational) axis of the driveshaft. In any of the preferred embodiments of the invention at least oneoutflow channel is located such that in a rotating drive shaft fluidwhich flows through the outflow channel along its axis forms at least athin layer of fluid between the solid support element and the wall ofthe treated vessel.

FIG. 1 illustrates, in a longitudinal cross-section, a distal portion ofone preferred embodiment of the rotational atherectomy device of anembodiment of the invention. The rotational atherectomy device iscomprised of an asymmetric abrasive element 101 which extends around theentire circumference of the drive shaft 2 proximal to and spaced awayfrom a distal end 6 of the drive shaft. The fluid impermeable driveshaft 2 is comprised by a fluid impermeable membrane 3 which lines atorque transmitting coil 4. Both the torque transmitting coil 4 and thefluid impermeable membrane 3 extend distally beyond the abrasive element101.

FIG. 1 illustrates an asymmetric distal support element 10 which has itscentre of mass spaced radially away from the longitudinal (rotational)axis W-W of the drive shaft 2. The Figure illustrates that at least oneoutflow channel 20 which extends through a heavier portion 60 of theasymmetric distal support element 10, the axis K-K of the outflowchannel 20 comprises an acute angle α of about ninety (90) degrees withthe longitudinal (rotational) axis W-W of the drive shaft. However, itwill be appreciated that there may be a plurality of outflow channels 20and the axes of these channels may form an acute angle of up to 30degrees with axis K-K of the most important outflow channel. Its axisK-K being oriented perpendicular to the longitudinal axis of the driveshaft. In the most preferred embodiment of the invention, axis K-K of atleast one outflow channel 20 passes through or close to the centre ofmass of the asymmetric distal solid support element.

FIGS. 1 and 2 illustrate that a portion of flushing fluid FF flowing inan antegrade direction through the drive shaft 2 is redirected throughthe outflow channel 20 into a vascular space of the treated vessel.

FIG. 2 illustrates that in a rotating drive shaft centrifugal forceattempts to press a rotating asymmetric solid distal support element 10against the wall 300 of the treated vessel but fluid exiting through theoutflow channel 20 along its axis K-K and forms an acute angle β of over75 degrees with an inner surface of a wall 300 of the treated vessel sothat fluid flowing through the outflow channel 20 forms a thin layer offluid between the solid support element 10 and an inner surface of thetreated vessel. This thin layer of fluid acts as a fluid bearing betweenthe asymmetric distal solid support element 10 and a wall 300 of thetreated vessel. At least a portion of fluid flowing through the outflowchannel 20 flows in a retrograde direction, as indicated by arrowsmarked “R”, and entrains abraded particles AP removed from the stenoticlesion 330. The retrograde flowing flushing fluid R and entrainedabraded particles AP are aspirated into a lumen of the drive shaftsheath 400.

FIG. 1 illustrates an asymmetric proximal support element 10 p which hasits centre of mass spaced radially away from the longitudinal(rotational) axis W-W of the drive shaft 2. The Figure illustrates thatat least one outflow channel 20 p extends through a heavier portion 60 pof the asymmetric proximal support element 10 p. The outflow channel 20p has an axis L-L which forms an acute angle α of about ninety (90)degrees with the longitudinal (rotational) axis W-W of the drive shaft.However, it will be appreciated that there may be a plurality of outflowchannels 20 p and the axes of these channels may form an acute angle ofup to 30 degrees with axis L-L of the most important outflow channelthat has its axis L-L oriented perpendicular to the longitudinal axis ofthe drive shaft.

FIGS. 1 and 2 illustrate that a portion of flushing fluid FF flowing inan antegrade direction through the drive shaft 2 is redirected throughthe outflow channel 20 p into a vascular space of the treated vessel.

FIG. 2 illustrates that in a rotating drive shaft centrifugal forceattempts to press a rotating asymmetric solid proximal support element10 p against the wall 300 of the treated vessel but fluid exitingthrough the outflow channel 20 p along its axis L-L forms an angle β ofabout ninety (90) degrees with an inner surface of a wall 300 of thetreated vessel so that fluid flowing through the outflow channel 20 pforms a thin layer of fluid between the solid support element 10 p andan inner surface of the treated vessel. This thin layer of fluid acts asa fluid beating between the asymmetric distal solid support element 10 pand a wall 300 of the treated vessel.

FIG. 3 illustrates a symmetric distal support element 10 s. The centreof mass of the symmetric distal support element 10 s coincides with thelongitudinal (rotational) axis W-W of the drive shaft 2. In a preferredembodiment of the invention at least a few outflow channels 20 s shouldextend radially outward through the symmetric distal support element 10s communicating a fluid impermeable lumen of the drive shaft 2 with avascular space of the treated vessel. Preferably said outflow channels20 s should be equally spaced around the maximum diameter circumferenceof the symmetric distal solid support element 20 s. FIG. 3 illustratesthat an axis M-M of at least one outflow channel 20 s comprises an acuteangle of over seventy five (75) degrees with the longitudinal(rotational) axis W-W of the drive shaft 2. In the preferred embodimentaxis M-M of the outflow channel 20 s forms an angle α of about ninety(90) degrees with the longitudinal (rotational) axis W-W of the driveshaft.

FIGS. 3 and 4 illustrate that a portion of flushing fluid FF flowing inan antegrade direction through the drive shaft 2 is redirected throughthe outflow channels 20 s into a vascular space of the treated vessel.

FIG. 4 illustrates that, in a curved vessel, the drive shaft 2 attemptsto maintain its straight configuration and therefore attempts to pressboth of the solid symmetric support elements towards the outer curvatureof the vessel and the symmetric abrasive element 102 towards the innercurvature of the vessel.

FIG. 4 illustrates that in a rotating drive shaft the axis M-M of theoutflow channel 20 s forms an angle β of about ninety (90) degrees withan inner surface of a wall 300 of the treated vessel so that fluidflowing through the outflow channel 20 s along its axis M-M forms a thinlayer of fluid between the solid support element 10 s and an innersurface of the treated vessel. This thin layer of fluid acts as a fluidbearing between the solid support element 10 s and a wall 300 of thetreated vessel. At least a portion of the fluid flowing through theoutflow channels 20 is flowing in a retrograde direction R and entrainsabraded particles AP removed (abraded) by the symmetric abrasive element102 from the stenotic lesion 360 located on the inner curvature of thevessel 300. The retrograde flowing flushing fluid R is aspirated into alumen of the drive shaft sheath 400.

FIG. 3 illustrates a symmetric proximal support element 10 sp. Thecentre of mass of the symmetric proximal support element 10 sp coincideswith the longitudinal (rotational) axis of the drive shaft 2. In apreferred embodiment of the invention at least a few outflow channels 20sp should extend radially outward through the symmetric proximal supportelement 10 sp communicating a fluid impermeable lumen of the drive shaft2 with a vascular space of the treated vessel. Preferably said outflowchannels 20 sp should be equally spaced around the maximum diametercircumference of the symmetric distal solid support element 20 sp. FIG.3 illustrates that an axis N-N of at least one outflow channel 20 spcomprises an acute angle of at least seventy five (75) degrees with thelongitudinal (rotational) axis W-W of the drive shaft 2. In thepreferred embodiment axis N-N of the outflow channels 20 sp forms anangle α of about ninety (90) degrees with the longitudinal (rotational)axis W-W of the drive shaft. FIGS. 3 and 4 illustrate that a portion offlushing fluid FF flowing in an antegrade direction through the driveshaft 2 is redirected through the outflow channel 20 sp into a vascularspace of the treated vessel.

FIG. 4 illustrates that in a rotating drive shaft the axis N-N of theoutflow channel 20 sp forms an angle β of about ninety (90) degrees withan inner surface of a wall 300 of the treated vessel so that fluidflowing through the outflow channel 20 sp along its axis N-N forms athin layer of fluid between the proximal solid support element 10 sp andan inner surface of the treated vessel. This thin layer of fluid acts asa fluid bearing between the proximal solid support element 10 sp and awall 300 of the treated vessel.

FIG. 3 illustrates an embodiment in which a fluid impermeable membranelines the torque transmitting coil. In an alternative embodiment,illustrated in FIG. 4, the fluid impermeable membrane is disposed aroundthe torque transmitting coil.

It will be appreciated that the device with symmetric support elementsis not intended to be exclusively used in curved vessels but can also beused successfully in straight vessels.

Many modifications and variations of the invention falling within theterms of the following claims will be apparent to a person skilled inthe art and the foregoing description should be regarded as adescription of the preferred embodiments only.

1. A rotational atherectomy device for removing a stenotic tissue from avessel of a patient, the device comprising an abrasive element mountedto a rotatable, flexible, hollow drive shaft having a longitudinal axisand a distal end, the abrasive element being mounted to the drive shaftbetween a distal solid support element and a proximal solid supportelement, the abrasive element being positioned proximal to and spacedaway from the distal solid support element which is mounted at thedistal end of the drive shaft, and the abrasive element being positioneddistal to and spaced away from the proximal solid support element, eachof the distal and proximal solid support elements being substantiallysmaller than the abrasive element and having a surface texture that isdifferent from an abrasive surface texture of the abrasive element, thedrive shaft comprising a torque transmitting coil and at least one fluidimpermeable membrane positioned radially inward of the torquetransmitting coil to form a fluid impermeable lumen along a centrallongitudinal axis of the drive shaft for an antegrade flow of fluidthrough the drive shaft, the distal solid support element having arounded outer surface and comprising an outflow channel which is influid communication with the fluid impermeable lumen of the drive shaftand which extends through the solid distal support element in agenerally radially outward direction with respect to the longitudinalaxis of the drive shaft, the outflow channel having an outflow openingin said rounded outer surface located such that, during rotation of thedrive shaft, said outflow opening is configured to output fluid flow forforming a fluid layer between the solid distal support element and awall of a vessel, said layer of fluid being operable to form a fluidbearing between the rotating solid distal support element and the wallof the vessel during rotation and back and forth movements of the driveshaft within the vessel, wherein said distal and proximal solid supportelements are configured to act as counterweights to the abrasiveelement.
 2. A rotational atherectomy device according to claim 1,wherein the solid proximal support element has a rounded outer surfaceand comprising an outflow channel which is in fluid communication withthe fluid impermeable lumen of the drive shaft and which extends throughthe solid proximal support element in a generally radially outwarddirection with respect to the longitudinal axis of the drive shaft, theoutflow channel having an outflow opening in said rounded outer surfaceof the solid proximal support element located such that, during rotationof the drive shaft, said outflow opening is configured to output fluidflow for forming a fluid layer between the solid proximal supportelement and the wall of the vessel, said layer of fluid being operableto form a fluid bearing between the rotating solid proximal supportelement and the wall of the vessel.
 3. A rotational atherectomy deviceaccording to claim 2, wherein the abrasive element and each of thedistal and proximal solid support elements have their individual centersof mass, the centers of mass of both the distal and proximal solidsupport elements being spaced radially away from a longitudinal axis ofthe drive shaft but in a direction diametrically opposite to thedirection in which a center of mass of the abrasive element is spacedradially away from the longitudinal axis of the drive shaft so that thedistal and proximal solid support elements act as counterweights to theabrasive element.
 4. A rotational atherectomy device according to claim1, wherein the fluid impermeable membrane lines the torque transmittingcoil.
 5. A rotational atherectomy device according to claim 1, whereinthe fluid impermeable lumen of the drive shaft is configured foradvancement of the drive shaft over a guidewire across a stenotic lesionto be treated and for transfer of pressurized fluid into the outflowchannel of the distal solid support element after crossing the stenoticlesion.
 6. A rotational atherectomy device for removing a stenoticlesion from within a vessel of a patient, the device comprising arotatable, flexible, hollow drive shaft having a longitudinal axis ofrotation and an abrasive element mounted proximal to and spaced awayfrom a distal end of the drive shaft, the drive shaft including a distalsolid support element located at the distal end of the drive shaft andspaced away from the abrasive element and including a proximal solidsupport element located proximal to and spaced away from the abrasiveelement, each of the distal and proximal solid support elements beingsubstantially smaller than the abrasive element and having a surfacetexture that is different from an abrasive surface texture of theabrasive element, the drive shaft having a fluid impermeable walldefining a fluid impermeable lumen for an antegrade flow of fluidthrough the drive shaft, wherein both the distal and proximal solidsupport elements have an outflow channel that is in fluid communicationwith the fluid impermeable lumen of the drive shaft and extend througheach of the support elements in a generally radially outward directionwith respect to the longitudinal axis of the drive shaft, the outflowchannels have axes that form angles of about ninety (90) degrees withthe longitudinal axis of the drive shaft and have outflow openings alongcircumferences of the support elements such that, during rotation of thedrive shaft, the outflow openings are configured to output fluid flowfor forming layers of fluid between the solid support elements and awall of the vessel, said layers of fluid being operable to form fluidbearings between the rotating solid support elements and the wall of thevessel during rotation and back and forth movements of the drive shaftwithin the vessel, wherein said distal and proximal solid supportelements are configured to act as counterweights to the abrasiveelement.
 7. A rotational atherectomy device according to claim 6,wherein the fluid impermeable lumen of the drive shaft is configured foradvancement of the drive shaft over a guidewire across a stenotic lesionto be treated and for transfer of pressurized fluid into the outflowchannels of both the distal and proximal solid support elements aftercrossing the stenotic lesion.
 8. A rotational atherectomy deviceaccording to claim 6, wherein the abrasive element and each of thedistal and proximal solid support elements have their individual centersof mass, the centers of mass of both the distal and proximal solidsupport elements being spaced radially away from the longitudinal axisof the drive shaft but in a direction diametrically opposite to thedirection in which a center of mass of the abrasive element is spacedradially away from the longitudinal axis of the drive shaft so that thedistal and proximal solid support elements act as counterweights to theabrasive element.
 9. A rotational atherectomy device according to claim6, wherein the fluid impermeable wall lines the torque transmittingcoil.